It is known to use multiple row harvesting heads in a harvesting apparatus, such as shown in the co-pending U.S. patent application of Eugene A. Sousek, Ser. No. 419,482, entitled Harvester Head Assembly. This state of the art equipment enables simultaneous harvesting of crops from multiple rows greatly increasing the efficiency of operation.
Typically, each multiple row head assembly includes a plurality of row units defining inlets to the harvester. Each row unit includes adjacent left and right endless gathering members driven by sprockets mounted on a support assembly. The gathering members convey the forage from a cutter adjacent the forward end of the row unit to a harvester at the rear end thereof. Should a gathering member break or become so loose as to work its way free of the sprockets over which it extends, it is drawn up into the harvester. There, the gathering member, a metal chain or rubber belt, causes damage by wedging and jamming in the feed rolls and/or chopper mechanism of the harvester. This, of course, results in the shut down of the harvester with the attendant costly down time and repairs. This need for a system that will prevent broken gathering members from being conveyed into and damaging the harvester has been identified in the past and attempted to be solved by others.
One attempt at solving the above-identified problem is found in Eistert et al. U.S. Pat. No. 4,199,924. In Eistert, a pressurized fluid cylinder is utilized to urge an idler sprocket away from a drive sprocket and tension the gathering member. The cylinder is equipped with a pressure responsive switch or valve that interrupts the harvester drive when the pressure in the cylinder drops below or exceeds a certain pressure range. Additionally, when the gathering member stretches beyond a certain limit or breaks, an arm connected to the cylinder rod is urged by the cylinder to engage and activate a micro-switch. Activation of the micro-switch causes interruption of the harvester drive by a clutch or other means suspending power to the drive sprocket, thereby preventing the chain from being conveyed into and damaging the harvester.
The Eistert apparatus, however, suffers from a number of deficiencies. It is quite complicated and expensive, relying on a series of blocking, checking and regulating valves in the pressurized lines between the cylinder and a pressurized fluid source. The apparatus is also expensive to manufacture and, as characteristic of pressurized systems, expensive to maintain. A leak or malfunction in any of the components renders the harvester inoperable due to loss of tension in the gathering chain. Additionally, repairs are difficult as each component must be separately checked to determine the source of the problem.
Further, Eistert's device is quite cumbersome. The pressure cylinder, multiple pressure lines and pressurized fluid source occupy a large area of the support assembly. In fact, the space requirements are such that the crop gathering and conveying apparatus must be designed around the Eistert device. There simply is no way to retrofit the Eistert system into row-head assemblies presently in production without a complete redesign. Also, the additional weight of the Eistert detecting system not only leads to increased fuel consumption but also causes accelerated metal fatigue of the mounts between the harvester and head assembly; a condition exacerbated by the cantilever fashion of mounting, the vibration from the rotating gathering members and the bumpy terrain over which the harvester travels.
Additionally, the slide connecting the cylinder to the idler sprocket in Eistert is subject to bending under the forces acting upon it through the gathering chain as the chain collects and conveys forage. Any bending that takes place compromises the efficient and effective operation of the Eistert system. There is thus a need for a crop gathering and conveying apparatus safety interlock system that is inexpensive to manufacture, repair and maintain. One that is small, lightweight and durable. A safety interlock system providing both improved efficiency and reliability.